MOSCOW — Russia stepped up efforts Friday to resolve a dispute with neighbor Kazakhstan over its demand to reduce the number of commercial satellite launches from the Russian-leased Baikonur cosmodrome.

Kazakhstan, which in the past suspended Russian rocket launches after previous failures spilled toxic rocket fuel, has demanded that Russia cuts the number of Proton rockets lifting off from Baikonur from 17 to 12 this year.

“The issue regarding the number of launches is linked to Kazakhstan’s concerns about their impact on environment,” Lavrov said. “Russia is taking all the necessary steps to address environmental aspects by using improved Proton-M booster rockets. There is no sensation about it, just working issues.”

The dispute has threatened to cloud relations between the two ex-Soviet neighbors. Moscow would lose half a billion dollars if Kazakhstan succeeds in cutting the number of launches, according to Russia’s pro-government daily Izvestia, which reported the Kazakh demand. The paper also said Moscow was threatening Kazakhstan with countermeasures.

Izvestia on Thursday quoted a note from Russia’s Roscosmos space agency warning that the country would opt out of joint projects with Kazakhstan if it doesn’t withdraw its demand for Russia to scale down its scheduled rocket launches from Baikonur.

Russia has a lease to use Kazakhstan’s Soviet-built launch pad until 2050 and pays an annual fee of $115 million. It has continued to rely on Baikonur for all its manned missions and most of its commercial satellite launches.

This isn’t the first time Kazakh authorities have voiced worries over the environmental impact of Russia’s space program. Previously, they have briefly suspended Russian launches from Baikonur following the spill of highly toxic rocket fuel after failed launches of the heavylift Proton booster rocket, the main cash cow of Russia’s space program.

Moscow also has the Plesetsk launch pad in the north of Russia but that is used mostly for launches of military satellites. It has moved to reduce its dependence on Kazakhstan by building a new cosmodrome in the far east.